Personally, I'd prefer not to know if there was something potentially wrong with me. Then I'd just end up sitting at home worrying about what might happen. While this is indeed a really sad case, especially given her family story, I hope it doesn't attract too much attention from the PC brigade who'll start to mandate medical certs and insurance premiums for events. No thanks

You'd prefer not to know if something was wrong with your heart? You do know doctors and surgeons can fix things, don't you?

Seriously though, unless there is something pretty obvious wrong, it's going to take a lot more than a blood test and check from a GP to find anything wrong. Since Fabrice Muamba was already brought up as an example, he would've gone through pretty extensive checks as a professional footballer, none of which uncovered a problem. In fact, even the checks he received at the chest hospital didn't show anything wrong - even after he collapsed.
If I was a more serious athlete, then I would consider it, but since I am not and my health is generally good (at least according to the last check up I had last year) I am happy enough.
Touch wood, please god, fingers crossed etc.

What is a comprehensive medical check? I'm doing my first marathon this year and need to get checked out.

Is it enough to get bloods and an ECG done?

A comprehensive medical for a serious enough runner should also have an echocardiogram, bloods and ecg's only tell so much. very sad that this has happened , but not surprising given the high volume of people running. but at least some good is coming from it and she not just another statistic,

What is a comprehensive medical check? I'm doing my first marathon this year and need to get checked out.

Is it enough to get bloods and an ECG done?

I'm not even sure an ECG is always necessary. There are known risk factors for heart disease which a GP could check you out with, that would decide if a stress ECG is worthwhile. The simplest test that doesn't even need a doctor is to get your blood pressure checked. A regular GP checkup should be adequate beyond that.